The objective of this project is to characterize the developmental course of shared attention between children and their social partners. This proposal focuses on the year-long period just after infancy when children typically become increasingly competent symbol users. The basic contention is that the coordination of attention to people and objects, an organization often called joint attention, is transformed as symbols draw distant events into on-going interactions. Three specific aims are pursued: to describe normative changes in shared attention; to characterize how symbols increase the scope and coherence of social interactions; and to investigate how variations in the timing of language onset and the integrity of joint attention skills influence the development of shared attention after infancy. Sixty children, 40 who are developing typically and 20 who have been diagnosed with autism (a disorder characterized by deficiencies in joint attention skills), will each be videotaped five times over a year as they interact with their mothers in a series of scenes that probe requesting. Social interacting, shared referring, and discussing past and future. The rate of language acquisitional will also be assessed. Videotapes will be coded to document the child's attention to people, objects, and symbols; the child's symbolic actions; and the mother's attention-directing actions toward symbols. Growth curves will be examined both to chart the course of symbol-infused attention as a function of language onset and to discern how autism may disturb the infusion of symbols into shared attention. This systematic study of a period of rapid developmental change will provide a fuller view of how children are introduced to symbols as they communicate with their caregivers. This view should further the formulation of models of representational development as well as inform understandings of pervasive developmental and disorders such as autism.